CVERadar
MEDIUM · CVSS 3.1 5.7Public PoCEPSS 0.63% (p50)Threat level 33

CVE-2023-1206: CVE-2023-1206: A hash collision flaw was found in the IPv6 connection lookup table in the Linux kernel’s …

linux · linux kernel · NVD published 2023-07-01 · posted 2025-12-01 · last modified 2026-10-15

What it is

A hash collision flaw was found in the IPv6 connection lookup table in the Linux kernel’s IPv6 functionality when a user makes a new kind of SYN flood attack. A user located in the local network or with a high bandwidth connection can increase the CPU usage of the server that accepts IPV6 connections up to 95%.

WeaknessCWE-400
CVSS vectorCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (source: [email protected])
ATT&CK tacticsImpact

Exploitation evidence

First exploit evidence seen: 2025-12-01 (earliest date across the sources below).

Exploited in the wild

No source on this site lists in-the-wild exploitation yet (CISA KEV, VulnCheck KEV).

Public exploit code

GitHub proof-of-concept repositories

1 public repositories from 1 accounts, first seen 2025-12-01. Most starred: SpiralBL0CK/CVE-2023-1206-CVE-2025-40040-CVE-2024-49882 (12 stars), view repository.

Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.

Sources: nomi-sec/PoC-in-GitHub.

How to fix it

Fixed versions

  • linux linux kernel: upgrade to 6.5 or later

Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.

Vendor advisories and patches

No vendor-tagged reference yet; see the full reference list.

MITRE ATT&CK mitigations for this chain

  • M1037 Filter Network Traffic (for T1499) : Leverage services provided by Content Delivery Networks (CDN) or providers specializing in DoS mitigations to filter traffic upstream from services. Filter boundary traffic by blocking source addresses sourcing the attack, blocking ports that are being targeted, or blocking protocols being used for transport. To defend

Detection Generic guidance

  • Impact: Monitor service availability, unexpected encryption activity and mass file changes.

Response checklist Generic guidance

  1. Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
  2. Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
  3. Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
  4. Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.

Sources